264 MOVEMENT 



four limbs being characteristic of an ordinary walking 

 pace.* 



Having taken breath, the tortoise returned to the 

 bi )ttom of the aquarium by a similar mode of progression. 



With other species, the marine turtle, for instance, 

 there are two distinct kinds of locomotion — firstly, that 

 of walking, which has just been described; and, secondly, 

 that which we have compared to flying. In this latter 

 method of progression, the hind limbs are stretched out 

 side by side, and are free from all movement, while the 

 fore limbs are moved backwards and forwards in the 

 execution of movements similar to those of the wings 

 of a " rowing " bird. 



The progression of land tortoise-; appeared to us to 



WW**** 



Fig. 185.— Quadrupedal movements of a fresh-water tortoise in swimming to the 



surface. 



resemble ordinary walking, but not having had time 



to tame a specimen, we did not succeed in inducing one 



to walk in front of the object-glass; the animal, no doubt 



frightened at the noise of the apparatus, obstinately 



kept its limbs tucked away under its carapace. 



Lizards are extremely difficult to deal with. To 



place one under favourable conditions for observation 



we made use of the circular canal which was represented 



in Fig. 50, and designed for studying subaqueous 



movements. The transparent part of this canal was 



lighted from beneath, and the photographic apparatus 



was placed at a higher level, and received its images 



reflected from a mirror obliquely inclined at an angle 



* Sec sequence of these movements in Chap, xi., " The Synoptic 

 Record of Huraes' Paces." 



